Genes on the edge: A framework to detect genetic diversity imperiled by climate change

Abstract

Ongoing global warming is disrupting several ecological and evolutionary processes, spanning different levels of biological organization. Species are expected to shift their ranges as a response to climate change, with relevant implications to peripheral populations at the trailing and leading edges. Several studies have analyzed the exposure of species to climate change but few have explored exposure at the intraspecific level. We introduce a framework to forecast exposure to climate change at the intraspecific level. We build on existing methods by combining correlative species distribution models, a model of species range dynamics, and a model of phylogeographic interpolation. We demonstrate the framework by applying it to 20 Iberian amphibian and reptile species. Our aims were to: (a) identify which species and intraspecific lineages will be most exposed to future climate change; (b) test if nucleotide diversity at the edges of species ranges are significantly higher or lower than on the overall range; and (c) analyze if areas of higher species gain, loss, and turnover coincide with those predicted for lineages richness and nucleotide diversity. We found that about 80% of the studied species are predicted to contract their range. Within each species, some lineages were predicted to contract their range, while others were predicted to maintain or expand it. Therefore, estimating the impacts of climate change at the species level only can underestimate losses at the intraspecific level. Some species had significant high amount of nucleotide at the trailing or leading edge, or both, but we did not find a consistent pattern across species. Spatial patterns of species richness, gain, loss, and turnover were fairly concurrent with lineages richness and nucleotide diversity. Our results support the need for increased attention to intraspecific diversity regarding monitoring and conservation strategies under climate change.

Genetic and demographic trends from rear to leading edge are explained by climate and forest cover in a cold‐adapted ectotherm

“…Hence, the preservation of these habitats might represent a key conservation action to protect this lizard and the associated cortege of species (Jofré et al., 2016). There is now a critical need for developing genetically informed ecological niche models to better predict future species distributions under cumulative constraints of climate change and landscape structuration (Carvalho et al., 2019; Ikeda et al., 2017; Razgour et al., 2019).…”

“…For each parameter, we estimated estimation accuracy by generating 500 datasets and compile the Relative Median Absolute Error (RMAE) based on their posterior distributions. (Carvalho et al, 2019;Ikeda et al, 2017;Razgour et al, 2019).…”

“…Causes are multiple, often synergetic, and have various footprints from genes to ecosystems (Pecl et al., 2017). As a consequence, many species’ distributions are shifting (Lenoir et al., 2020; VanDerWal et al., 2013) and these range shifts have direct impacts on processes and patterns of population genetics (Carvalho et al., 2019; Hampe & Petit, 2005; Templeton et al., 2001). In particular, once populations at the rear edge become isolated, the loss of connectivity and immigration progressively leads to an increase in inbreeding through genetic drift, one of the main precursors of decline in small populations (Frankham, 2010; Hampe & Petit, 2005).…”

Evaluating surrogates of genetic diversity for conservation planning

“…As a consequence, there has been growing interest in identifying surrogates for genetic diversity (Carvalho et al 2011;Ponce-Reyes et al 2014;Hanson et al 2017). Prioritizations should ideally represent intraspecific genetic diversity at multiple scales (Beger et al 2014;Carvalho et al 2019). At the site level, prioritizations should represent sites that each have a diverse group of genotypes (hereafter, site-level genetic diversity [akin to alpha diversity]) (Petit et al 1998) because such sites can harbor demographically stable populations and replenish declining populations (Smith et al 2014).…”

“…2014; Carvalho et al. 2019). At the site level, prioritizations should represent sites that each have a diverse group of genotypes (hereafter, site‐level genetic diversity [akin to alpha diversity]) (Petit et al.…”